Sensor for oxygen activity measurements in glass melts

Traditional oxygen activity measurement in glass melts is based on Y2O3-stabilized ZrO2 which, in continuous use in the glassworks, is subjected to considerable wear. The present paper describes an oxygen sensor that is not equipped with wear parts. The new sensor is far less sensitive to temperature gradients in the surrounding area than ZrO2 sensors; the oxygen measurement, however, is greatly disturbed at direct flame irradiation

Electrochemical measurements of oxygen activity of glass melts in glass melting furnaces

The electrochemical determination of the oxygen activity of a glass melt by a stabilized ZrO2 sensor was established as an online measurement in a working chamber and a feeder channel. Α method is described to take the temperature difference between the sensor's electrodes into account. In green glass a correlation between the oxygen activity and Fe2+/Fetot ratio, in amber glass a correlation between oxygen activity and Cr2O3 content are found

Connexin Hemichannel Composition Determines the FGF-1–induced Membrane Permeability and Free [Ca2+]i Responses

Cell surface hemichannels (HCs) composed of different connexin (Cx) types are present in diverse cells and their possible role on FGF-1–induced cellular responses remains unknown. Here, we show that FGF-1 transiently (4–14 h, maximal at 7 h) increases the membrane permeability through HCs in HeLa cells expressing Cx43 or Cx45 under physiological extracellular Ca2+/Mg2+ concentrations. The effect does not occur in HeLa cells expressing HCs constituted of Cx26 or Cx43 with its C-terminus truncated at aa 257, or in parental nontransfected HeLa cells. The increase in membrane permeability is associated with a rise in HC levels at the cell surface and a proportional increase in HC unitary events. The response requires an early intracellular free Ca2+ concentration increase, activation of a p38 MAP kinase-dependent pathway, and a regulatory site of Cx subunit C-terminus. The FGF-1–induced rise in membrane permeability is also associated with a late increase in intracellular free Ca2+ concentration, suggesting that responsive HCs allow Ca2+ influx. The cell density of Cx26 and Cx43 HeLa transfectants cultured in serum-free medium was differentially affected by FGF-1. Thus, the FGF-1–induced cell permeabilization and derived consequences depend on the Cx composition of HCs